using System;
public class Demo {
    public static void Main(string[] args) {
        // System.Threading.Timer timer = new System.Threading.Timer(new System.Threading.TimerCallback(TimerCallback), null, 0, 1000);
        Console.ReadLine("hello world");
    }

    private static void TimerCallback(object state) {
        Console.WriteLine("TimerCallback called at {0}", DateTime.Now);
    }
}